Project "Dictogrand Dictograph R-3 Horn Speaker" (2/2)

I managed to fix this speaker up the way I wanted it, and I have to say it works beautifully!

I replaced the cardboard mini horn with a metal one with nearly the exact dimensions. I basically went into Daiso one fine day and went around with the cardboard horn/funnel and tried to find something as close and possible and I'd say I found something very close!

Not bad for $2 eh?

It is a measuring cup meant for bartenders to measure out shots for drinks and it is made of stainless steel.. perfect for my intended use! Just cut it at the joint and make a hole at the end and it is now a mini metal horn!

Like so!

Using a metal cone/horn gives much more clarity in sound over the cardboard one, which to me sounded very bloated and muffled. I read up on the basics of using horns to amplify sounds and the design of the Dictogrand's horn amplifies the middle to high frequencies while attenuating the lower frequencies. In other words: you won't be hearing much bass coming out of the horn, which is okay because I didn't intend to use the horn for dance music anyway! Initial testing showed me that the horn speaker shines when playing acoustic music with uncomplicated arrangements, i.e: simple chill-out tones that do not have an overwhelming amount of instruments.

Moving on, I kept in mind that everything I planned to put into the box of the speaker should be kept replaceable in the event something better comes along in the future. Thus no epoxy or nails should be used or at least kept to a minimum. I attached this metal horn to the horn entrance plate by using hot glue, which can be easily peeled or dissolved with alcohol in the future if needed but strong enough to hold things together for a long time.

The last piece of the puzzle was extending the microUSB charging port from the X-Mini to the outside of the box. I couldn't find any proper microUSB breakout boards that could be mounted vertically and thus had to ask my brother who very graciously provided me with a solution by making one (or two) from scratch. 

Tiny!

I ended up only using 2 pins out of the 5 shown there for +5V and GND which are used for charging. It is possible to use the data pins on the X-Mini for audio playback but I intended to use the 3.5mm jack for that so I kept those pins unconnected. In the process of hooking this USB board up to the speaker I absolutely forgot to take a picture of it wired up before sticking it in. I basically got a standard microUSB cable (also from Daiso by the way!) and cut off one end. I soldered the +5V and GND wires to this breakout board and connected the other end of the cable to the microUSB port on the X-Mini.

All there was left to do was to drill the holes required and fine tune them with a file. I got my father to help with his experienced drilling skills and I fine tuned the holes ever so slightly for a nice fit.

As the interfaces were already extended out as shown previously in part 1 of this post, all I had to do now was put in the switches and jacks and wire them all up. The X-Mini is secured snugly in place by the isolating foam below and behind it, which is forcing it up against the metal horn. I tried shaking the box repeatedly and saw that the speaker did not budge at all so I decided against using any glue or other measures to hold it down.. all in the name of semi-temporal-permanent-ism! You never know if a year from now they come out with the X-Mini Uno EXTREME and I'd be kicking myself while I'm tearing out all the permanent fixtures I made previously to this current speaker. It isn't pretty now I'd admit that, but it will work just fine.

Power switch in place, ready to be wired up

You can see the microUSB port in the picture below on the right below the 3.5mm jack. I applied a generous amount of hot glue to the parts that would be enduring a lot of pushing and pulling.

The volume potentiometer was glued on to a horizontal balsa wood support (also from Daiso! Daiso has everything!) and aligned with the Dictogrand's volume knob, which I forgot to mention, was cut down to a much more manageable length as shown below so that it could turn the X-Mini's volume potentiometer with ease.

Hot glue; it ain't pretty, but it gets the job done!

Finally, I put another piece of isolating foam on the top of everything so that when I close the lid of the box it would sandwich the speaker in place very tightly.

The LED lights up blue when the speaker is turned on, and it changes to red when the USB charging cable is plugged in. The battery in the X-Mini is only 550mAh and is easily replaceable with another battery of a bigger capacity, but that would be a side-project for another time. Also, it is possible to power the speaker solely by USB power alone, so if the battery ever dies one day then the speaker would still be usable by plugging in a microUSB cable.

To celebrate the completion of this speaker, I made myself a 'commemorative' 3.5mm interconnect cable to always be used by this speaker. Just plug one end into the speaker and the other end to any compatible device like an iPhone or a MP3 player and it is good to go!

And that.. is the story of how I got myself a snazzy horn speaker after all!

It works wonderfully with jazz and easy-listening music, or period-correct music, if you will (tunes from the 1920s onwards to the 1970s). What the horn does is add a touch of reverb to every sound, so you can hear an echo that lingers after every note for a few milliseconds which is completely natural due to the acoustical design of the horn.

(Link to part 1/2)